1. Field of the Invention
The present invention relates to a process for producing stretched articles of conjugated polymers and highly conductive compositions of said stretched article and a dopant. These compositions are useful as a conductive polymer material.
2. Description of the Prior Art
It is known that stretched molded articles of conjugated polymers can be obtained by a process of thermally stretching a conjugated polymer or by a process of thermally decomposing a precursor polymer to obtain a conjugated polymer and simultaneously thermally stretching the precursor polymer. It is further known that compositions between said molded article of a conjugated polymer and a dopant can also be obtained. With respect to the latter stretching process, in particular, stretched molded articles of conjugated polymers having a high stretch ratio as well as their compositions with a dopant are reported. In this connection, a stretched poly(p-phenylene vinylene) film obtained by subjecting a film of a soluble precursor polymer prepared via sulfonium salt route to thermal decomposition and thermal stretching, as well as its composition with a dopant are known. For example, a stretched film of poly(p-phenylene vinylene) obtained by subjecting a p-xylylenedimethylene-bis(sulfonium salt) to condensation polymerization, subjecting the resulting polymer to cast molding, subsequently to elimination of the sulfonium salt group, and then to thermal stretching is known to have, when made into a composition with a dopant (arsenic pentafluoride), a conductivity of 2,790 S/cm (U.S. Pat. No. 4,528,118).
However, conjugated polymers, being rigid, insoluble and infusible, give stretched molded articles of low stretch ratio when merely subjected to thermal stretching. Molded articles of high stretch ratio can be obtained by producing a precursor film from a soluble precursor polymer and subjecting the film to thermal decomposition and thermal stretching; however, rigid conjugated polymers are also formed during stretching and accordingly the molded articles have a limit in stretch ratio. Further, conductive compositions produced therefrom have a maximum conductivity of 2,790 S/cm, which is not sufficiently high in practical application.